1. Field of the Invention
The present invention relates to a holder member fixing apparatus of a motor, and more particularly to holder member fixing apparatus of a motor for enhancing assembling efficiency by maintaining a fixing position constantly without using a separate jig when a holder member rotatably supporting a rotor is fixedly installed to the upper portion of a substrate.
2. Description of the Prior Art
Generally, as shown in FIG. 1, a motor is formed by a separated stator 3 and rotor 4. Stator 3 includes a core 5 laminated in a disc form, and a coil 5a wound around the outer periphery of core 5. Stator 3 is fixedly installed on a printed circuit board 2 formed on the upper portion of a substrate 1. That is, after being seated onto the outer periphery of a holder member 3a upwardly installed on the center of printed circuit board 2, core 5 is fixed to the upper portion of substrate 1 by means of a screw 3b. Also, rotor 4 is equipped with a cap-shaped case 6a which encloses the upper portion of core 5, and a ring-like magnetic body 6 is fixedly installed to the inner periphery of case 6a. Here, magnetic body 6 is alternately provided with n poles and s poles, and a rotating shaft 6b in the center of case 6a is rotatably coupled to holder member 3a.
In the conventional motor constructed as above, when current is applied to coil 5a via printed circuit board 2, a magnetic force is produced on magnetic body 6, and case 6a forming rotor 4 is rotated about rotating shaft 6b. At this time, rotating shaft 6b is rotatably supported by holder member 3a to maintain the rotating accuracy of case 6a.
In the conventional motor, however, handling of holder member 3a is fastidious because a lubricating oil is used for holder member 3a to decrease friction with rotating shaft 6b. That is, holder member 3a which is to be fixed to the upper surface of printed circuit board 2 becomes slippery which makes it difficult to set its fixing position accurately. If the fixing position is inaccurate due to this fact, the position of core 5 on the upper portion of holder member 3a becomes erroneous every product. What's worse, the relative position of a hole device formed on the upper surface of printed circuit board 2 and core 5 is varied. In other words, when the hole device is hidden by core 5, the hole device cannot sense the exact position of magnetic body 6 and a problem of degrading motor performance is obtained. Accordingly, a separate jig is employed to arrange the assembling position of holder member 3a . This lowers workability while the assembling position differs in accordance with the skillfulness of a worker to thereby have a drawback of lowering the performance of the product.
FIG. 2 is a sectional view showing another example of the conventional holder member fixing apparatus, in which a hole 7a is formed in the of printed circuit board 2, and a projection 7 is formed at the lower portion of holder member 3a. Then, by inserting projection 7 into hole 7a, the fixing position is set. But there is a problem of gripping holder member 3a when fixing it while holder member 3a is inserted into hole 7a to prevent it from movably rotating.
FIG. 3 is a sectional view showing still another example of the conventional holder member fixing apparatus, in which a hole 8a is formed in the printed circuit board 2, and a projection 8 protrudes from the of substrate, and is inserted into hole 8a. After projection 8 is inserted into hole 8a, holder member 3a is fixed to the upper surface of projection 8. In this example, however, holder member 3a is free when being placed onto the upper surface of projection 8 which makes assembly difficult to necessitates a separate jig.